The field of invention relates to container apparatus and more particularly relates to a variable-length dip tube suitable for connection to a pump or valve at an opening of a container. It is particularly useful in the field of chemical transfer drums or tank-like containers designed for returnable circuit use and equipped with dry-break (dripless) valve(s) in an upper wall.
Dry-break valves in drum containers find widespread application in the agricultural and veterinary fields, for example. In those fields, toxic, concentrated liquid herbicides, insecticides and lousicides, among other substances, are provided for dilution preceding application to farm crops and animals, as the case may be. A widespread delivery method involves 110 litre (30 US gallon) capacity drums that have, in the head (upper end) of the drum, a dry-break valve such as one provided by Micromatic Operations Inc of Holland, Mich. The particular valve employed is not crucial to the invention, nor is the capacity of the drum.
The Micromatic valve has a polyethylene dip tube that leaves room for improvement. Many of the typically contained dangerous substances that are packaged in returnable circuit containers are prone to cause environmental stress-cracking. This combined with shape and usage stress factors cause the known dip tube to fail by mechanisms including excessive bending resulting in blocking off the end or cracking at the end. This prevents full removal of contents, resulting in dissatisfaction.
The present invention, described more fully below, seeks to avoid those disadvantages.
The invention provides a variable-length dip tube suitable for connection to a closure for a container comprising: a first tube and a second tube, one of which is attachable to a closure for a container, the first tube is of a fixed length and is adapted to fit inside the second tube, the second tube has a collapsible and extensible portion intermediate an upper and lower and portions of the second tube, at least a part of the upper end portion being in fluid tight contact with the first tube at a distance from the lower end of the first tube, said collapsible and extensible portion and said lower end portion being a loose clearance fit over the first tube.
The dip tube is usually inserted through a threaded opening in the top end of a container, with the opening of the container then made leak tight by screwing in the pump or valve, via an adaptor, to the opening. Dip tubes according to the invention allows for containers of varying height. When the collapsible/extensible portion of the dip tube is in its fully extended, relaxed state in a container, adjusts in length as its lower end contacts the bottom of the container. The container may have a small well in the base that pools the last remaining drum content. The bottom of the dip tube may have a xe2x80x9cfootxe2x80x9d structure to allow liquids to enter its lower end freely. If the drum has a well, the foot fits inside that well.
The collapsible portion is preferably in the form of a compressible and extensible concertina bellows portion.
Optionally, the dip tube as described above may have a location cuff extending radially outwardly from the outside surface of the first tube at a pre-determined distance from its lower end.
The dip tube preferably comprises a distance from the cuff to the lower end of the longer tube greater than the length of the concertina bellows portion of the shorter tube when the bellows portion is uncompressed.
The dip tube may be provided with a foot portion at the lower portion of the second tube. This may involve the foot portion and lower portion comprising a single piece or may require the attachment of one to the other by any suitable attachment means.